This invention relates to a circuit arrangement for operating a lamp, provided with
terminals for connection to a supply voltage source, PA1 rectifying means provided with a first output and a second output and coupled to the terminals, for rectifying an AC voltage supplied by the supply voltage source, PA1 a DC-AC converter provided with a first input and a second input, coupled to the respective outputs, PA1 a first branch comprising first capacitive means and interconnecting the inputs, PA1 a second branch comprising a series circuit of first inductive means and second capacitive means and connecting the first output to the second output, PA1 a third branch comprising a series circuit of two unidirectional elements and connecting a common junction point of the first inductive means and the second capacitive means to the first input, and PA1 a fourth branch, comprising third capacitive means and connecting a common junction point of the unidirectional elements to a point of the DC-AC converter at which a high-frequency voltage is present during lamp operation. PA1 a fifth branch which comprises a series circuit of two further unidirectional elements and which connects the second input to a common junction point of the second capacitive means and the second inductive means, and PA1 a sixth branch which comprises fourth capacitive means and which connects a common junction point of the further unidirectional elements to a point of the DC-AC converter at which a high-frequency voltage is present during lamp operation.
Such a circuit arrangement is known from European Patent Application 0 244 644, which corresponds to U.S. Pat. No. 4,782,268 (Nov. 1, 1988). In the known circuit arrangement, the first branch acts as a filter whose function is, inter alia, to improve the power factor of the circuit arrangement. To fulfill this function satisfactorily, the self-inductance of the first inductive means is chosen to be comparatively great, so that the first inductive means form a voluminous and expensive component of the circuit arrangement.